1. Field of the Invention
The present invention relates to data acquisition and telemetry communication systems, but more particularly the present invention relates to an apparatus for acquiring data from underwater sites using both an optical communications link and a radio frequency communications link.
2. Description of the Prior Art
In the development of underwater ordnance, for example, and for diverse other purposes such as pollution monitoring, there is a common requirement to acquire data from underwater sensors. In the past, in order to carryout the necessary experiments for development and to acquire the data pertaining thereto, the underwater sensors plus associated equipment such as sensor platforms, hydrophone arrays, and cable connection boxes were planted at various depths on the ocean floor in suitable test areas. Thus, over the years, the ocean floor, in the aforementioned test areas, has become crisscrossed and crowded with electrical cables that have to supply power from a shore installation to the aforementioned underwater sensors and associated equipment, and acquire data from the underwater sensors and deliver this data to the shore installation for subsequent reduction and analysis. These cables, in the particular test site of interest, if laid end-to-end, would extend over 500 kilometers. Consequently, there is a need in the prior art to obviate the requirement for the kind of protracted cable-laying operations that are involved in planting shore-powered underwater sensors and associated equipment that receive power and send data through parallel multiconductor and multiplexed coaxial links.
As further background material, U.S. Pat. No. 4,259,746, filed Oct. 26, 1979, to Sandstedt, entitled, "Electrical Communications System", discloses an apparatus for communicating electrical signals (digital and/or analog) from one location to another first over an RF communications link and then over an optical communications link. The apparatus is configured so that data can be conveyed from a local source of diverse signals to a remote data terminal having a memory for storing the data which upon demand can output the data to one or more selected diverse utilization devices.
The prior art, as indicated hereinabove, include advances in data acquisition systems, including the use of the combination of RF and optical communications links. However, insofar as can be determined, no prior art data acquisition system having fiber optic and radio hybrid telemetry is configured to acquire data from underwater sites on a recurrent basis like the present invention. In addition, as far as is known, no prior art data acquisition system configured for in-water use incorporates all of the features and advantages of the present invention.